Numerous plug connectors and connecting devices are known in prior art which provide, with appropriate means, to automatically achieve the short-circuit upstream of the removable connector element (connector plug) before the complete opening of the contacts of the same, to avoid opening, hence leaving it “unladen”, the electric circuit upstream of the device itself.
For example, U.S. Pat. No. 4,988,307 describes a plug connector system that comprises a pair of contacts which are shorted between them until not mated with another pair of contacts, by means of a device operated by a spring. Said spring is however made captive in the insulating body of the plug connector and both its end portions act as spring towards their respective electric contact elements. The insulating body of the connector has a groove (slot) in which the median part of the elastic element is made captive. The spring is largely in the shape of a Z. The contacts of the first plug connector half are one male and one female, those of the corresponding second plug connector half are respectively female and male. The female contacts are surrounded by a tube of insulating material which, interposed between the contact and the spring determines, during the mating of the two plug connector halves, the opening of the short circuit.
The patent U.S. Pat. No. 4,988,307 (ITT Corp.) provides contacts equipped of a wrap-around tubule made of insulating material and an actuator pin having a shaped tip with an inclined plane (wedge) that operates the deflection of an arm of an elastic spring element.
All the known embodiments are complex, incorporating additional contact elements in series, or elastic elements, like pressure springs, additional to the element that realizes the short-circuit, the assembly resulting in such a way complex, the cost high and the reliability compromised.